The present invention generally relates to semiconductor manufacturing process and, more particularly, relates to a method for manufacturing field emitters by means of laser-induced re-crystallization.
In recent years, field emitters have been developed and widely used in electronic applications such as field emission displays (FEDs), backlight units, field emission transistors and field emission diodes. When subjected to a suitable electrical field, electrons are emitted from the field emitters and impinge on phosphors coated on the back of a transparent cover plate to produce an image or light. Such a cathodoluminescent process is known as one of the most efficient methods for generating light. Typically, the field emitters can be implemented by means of an array of micro-tips or carbon nano-tubes.
In the early development for field emitters, a so-called spindt tip process for forming metal micro-tips was utilized. In such a process, a silicon wafer is first oxidized to produce a thick silicon oxide layer and then a metallic gate layer is deposited on top of the oxide. The metallic gate layer is then patterned to form gate openings, while subsequent etching of the silicon oxide underneath the openings undercuts the gate and creates a well. A sacrificial material layer such as nickel is deposited to prevent deposition of nickel into the emitter well. Molybdenum is then deposited at normal incidence such that a cone with a sharp point grows inside the cavity until the opening closes thereabove. An emitter cone is left when the sacrificial layer of nickel is removed.
In an alternate design, silicon micro-tip emitters can be formed by first conducting thermal oxidation on silicon and then followed by patterning the oxide and selectively etching to form silicon micro-tips.
However, a major disadvantage of the micro-tip emitter is the complicated processing steps that must be used to fabricate the device. For instance, the formation of the various layers in the device, and specifically the formation of the micro-tips, requires a thin film deposition technique followed by a photolithographic and etching process. As a result, numerous process steps must be performed in order to define and fabricate the various structural features. The film deposition processes, photolithographic processes and etching processes involved greatly increase the manufacturing cost thereof.